1. Field of the Invention
The present invention relates to a power device and more particularly to a power device that has a plurality of light sources as loads and controls the light sources to be respectively turned on.
2. Background Art
As a power device or a lighting controller constructed so as to control the light source of a lighting device for a vehicle to be turned on, a device has been known that uses a switching regulator capable of controlling an output voltage to a light source in accordance with the current of the light source. In the switching regulator, even when a plurality of light sources are connected in series or in parallel with each other, the switching regulator can control a specified current to be supplied respectively to the light sources. Thus, an electric efficiency can be enhanced, a heat generation can be prevented and the light source can be serviceably miniaturized and thinned. However, the number of parts in the switching regulator is large. Further, when a plurality of light sources having different electric power from one another or different kinds of light sources are turned on, if one switching regulator is used for one light source, a circuit scale is enlarged and cost is increased.
Thus, a lighting controller using a time sharing system has been proposed that can supply an electric power to a plurality of different light sources by one switching regulator (see Patent Document 1). In this lighting controller, the plurality of light sources are sequentially selected at respectively designated timing, the output voltage of the switching regulator is applied to the selected light source and the output voltage of the switching regulator is controlled in accordance with electric current supplied to the selected light source.
[Patent Document 1] JP-A-2004-134146 (from page 3 to page 6, FIG. 1).